The present invention relates generally to automotive electronic control assemblies, and more particularly to electronic control assemblies containing printed circuit boards.
Automotive electronic control assemblies are well known in the art, however, they contain several distinct disadvantages. Most often the assemblies contain a relatively small printed circuit board heavily populated with electrical traces and components. Furthermore, these assemblies must be contained within a thick housing that increases the overall mass of the assembly. Moreover, the housings are then required to be filled with a potting material to ensure that the components and connections are kept clean of various materials that may infect the assembly. In addition, the printed circuit board has an RF ground that is typically mechanically attached to a ground member. This type of assembly lacks in that it is heavy and has poor heat sink capabilities.
Some assemblies have attempted to solve some of these problems by bending the assembly upon itself, such assemblies are disclosed in U.S. Pat. Nos. 5,998,738; 5,103,375; 5,170,326. These assemblies attempt to reduce the volume and weight of the assembly overall. However, the disclosures also contain areas of needed improvement. Most of these assemblies disclose a mandrel about which the assembly is bent and this mandrel is not removed. This internal mandrel unit increases the weight of the assembly. Furthermore, these disclosures require either a non-continuous printed circuit board or a unique and labor intensive adhesive process. All of these are disadvantages of the previous art.
According to the present invention a printed circuit board is adhered to a rigidizer plate whereupon the entire unit can then be bent over itself to create a compact assembly which can be substantially smaller, but contain the same number of traces and electrical components as a flat printed circuit board. Further, the present invention discloses a complete assembly which is sealed on each edge of the rigidizer by inserting the edge into a panel with a groove. The panel can be a plate, casting or an extrusion. This assembly provides a secure fit that provides great stability with a reduction in weight and volume.
Furthermore, according to the present invention a thermal pad design is provided to heat sink thermal energy, created by components on a printed circuit board, to a rigidizer/heatsink plate. First, the printed circuit board is adhered to the rigidizer plate with an adherent that is thermally conductive and compliant. Moreover, the printed circuit board contains pads with thermal vias to dissipate heat from components to the rigidizer plate.
Additionally, the rigidizer plate is formed so as to minimize stresses placed upon the printed circuit board during bending and after being bent. The present invention, while reducing stresses, provides for a printed circuit board adhered to the rigidizer plate and openings in the rigidizer plate to minimize stresses during bending. The bending area can also be removed with the use of a breakaway piece.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.